client.pcache-use test failing flakily on Travis

This happened twice now. The first time was in PR #3441. I re-started just that job and it then passed. It failed again in https://travis-ci.com/DynamoRIO/dynamorio/jobs/184740308

196/308 Test #190: code_api|client.pcache-use ...................................***Failed  Required regular expression not found.Regex=[^thank you for testing the client interface
Estimation of pi is 3\.142425985001098
successfully resurrected at least one pcache
$
]  1.08 sec
thank you for testing the client interface
Estimation of pi is 3.142425985001098